It is currently 08 Dec 2019, 20:20
My Tests

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

For the circle in the xy-plane, find the following. 22( x−1)

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Founder
Founder
User avatar
Joined: 18 Apr 2015
Posts: 8962
Followers: 178

Kudos [?]: 2119 [0], given: 8312

CAT Tests
For the circle in the xy-plane, find the following. 22( x−1) [#permalink] New post 24 May 2019, 08:19
Expert's post
For the circle \(( x−1)^2 +(y+1)^2 =20\) in the xy-plane, find the following.

(a) Coordinates of the center

(b) Radius

(c) Area

[Reveal] Spoiler: OA
(a) (1,-1) (b) \(\sqrt{20}\) (c) \(20 \pi\)


Math Review
Question: 20
Page: 245
Difficulty: medium

_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

1 KUDOS received
GRE Instructor
User avatar
Joined: 10 Apr 2015
Posts: 2612
Followers: 95

Kudos [?]: 2818 [1] , given: 45

CAT Tests
Re: For the circle in the xy-plane, find the following. 22( x−1) [#permalink] New post 09 Aug 2019, 11:13
1
This post received
KUDOS
Expert's post
Carcass wrote:
For the circle \((x−1)^2 +(y+1)^2 =20\) in the xy-plane, find the following.

(a) Coordinates of the center

(b) Radius

(c) Area

[Reveal] Spoiler: OA
(a) (1,-1) (b) \(\sqrt{20}\) (c) \(20 \pi\)


Math Review
Question: 20
Page: 245
Difficulty: medium


KEY CONCEPTS: The equation \((x−a)^2 +(y-b)^2 = r^2\) represents a circle with:
Center (a, b)
Radius = r



GIVEN: \((x−1)^2 +(y+1)^2=20\)
Rewrite as: \((x−1)^2 +[y+(-1)]^2 =(\sqrt{20})^2\)

This means....
(a) Coordinates of the center
Answer: (1, -1)

(b) Radius
Answer: \(\sqrt{20}\) (aka \(2\sqrt{5}\))

(c) Area
Area of circle = \(\pi r^2 = \pi(\sqrt{20})^2 = 20\pi\)

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com
Sign up for my free GRE Question of the Day emails

Intern
Intern
Joined: 09 Aug 2019
Posts: 30
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: For the circle in the xy-plane, find the following. 22( x−1) [#permalink] New post 09 Aug 2019, 14:20
Thanks! Great stuff!
1 KUDOS received
Intern
Intern
Joined: 16 Sep 2019
Posts: 13
Followers: 0

Kudos [?]: 9 [1] , given: 0

Re: For the circle in the xy-plane, find the following. 22( x−1) [#permalink] New post 18 Nov 2019, 22:22
1
This post received
KUDOS
Carcass wrote:
For the circle \(( x−1)^2 +(y+1)^2 =20\) in the xy-plane, find the following.

(a) Coordinates of the center

(b) Radius

(c) Area

[Reveal] Spoiler: OA
(a) (1,-1) (b) \(\sqrt{20}\) (c) \(20 \pi\)


Math Review
Question: 20
Page: 245
Difficulty: medium


The general equation of a circle is \((x-a)^2 + (y-b)^2 = r^2\)
where (a,b) is the centre and r is the radius.
Comparing with the values given in the question, we get the a = 1, b = -1 and r^2 = 20.
Centre = (1,-1)
Radius = \(\sqrt{20}\) = 2\(\sqrt{5}\)
and area = pi*r^2 = 20pi
_________________

If you like my solution, do give kudos!

Re: For the circle in the xy-plane, find the following. 22( x−1)   [#permalink] 18 Nov 2019, 22:22
Display posts from previous: Sort by

For the circle in the xy-plane, find the following. 22( x−1)

  Question banks Downloads My Bookmarks Reviews Important topics  


GRE Prep Club Forum Home| About| Terms and Conditions and Privacy Policy| GRE Prep Club Rules| Contact

Powered by phpBB © phpBB Group

Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.